FORMALIN AS A PERIPHERAL NOXIOUS STIMULUS CAUSES A BIPHASIC RESPONSE IN NUCLEUS PARAGIGANTOCELLULARIS NEURONS

Authors

  • E SOLEIMAN-NEJAD From the Dept. of Physiology. Faculty of Medicine. Army University of Medical Sciences. Po. Box: 14185- 611. Tehran
  • S SEMNANIAN the Institute of Biochemistry and Biophysics. Tehran University. Po.Box: 13145-1384. Tehran.l.R. Iran.
  • Y FATHOLLAHI The Dept. of Physiology. School a/Medical Sciences. Tarbiat Modarres University. Po. Box: 14115-111. Tehran.
Abstract:

The effects of formalin as a peripheral noxious stimulus on the activity of lateral paragigantocellularis nucleus (LPGi) neurons were examined. Spontaneous activity ofLPGi neurons was recorded after confirmation of their responsiveness to acute pain, and thereafter formalin (50 µL, 2.5%) was injected in the contralateral hindpaw. The response of the LPGi neurons was monitored for 60 min. A biphasic response with a peak lasting 3 to 5 min post-injection, and a second more prolonged tonic excitatory response were obtained which corresponds to the nature and time course of behavioral studies. It is concluded that LPGi neurons may be involved in the processing of nociceptive information related to formalin as a noxious stimulus.

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Journal title

volume 15  issue 4

pages  231- 236

publication date 2002-02

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